Recently much effort has been focused on the development of an EUV (Extreme Ultra-Violet) light source for the next generation photo-lithography in large-scale manufacturing. The wavelength of 13.5 nm was chosen because Mo/Si multilayer mirrors have very high reflectivity around this wavelength. One of the candidates of the light source is a laser-produced plasma of xenon. For modeling and optimization of the EUV plasma, spectroscopic data about multiply charged Xe ions is strongly desired. However, the energy levels and optical transitions of multiply charged Xe ions have not been established yet, because of their complexity coming from strong electron correlation.

We measured the photon emission spectra from excited multiply charged Xe ions in the EUV region of 6 - 24 nm in order to provide the spectroscopic information about these ions. Xe ions are produced in a 14.25 GHz ECR (Electron Cyclotron Resonance) ion source at Tokyo Metropolitan University. The ion beam extracted from the ion source with an electric potential of 20 kV is selected in respect of the mass-to-charge ratio, and directed into a collision chamber in which the ion beam interacts with a target gas jet. The EUV emission following electron transfer into the multiply charged ion is observed at the right angle to the ion beam with a compact grazing incident spectrometer.

The EUV measurement has been performed with the incident Xe^q+ ions of q = 8 - 17 and the rare gas targets of He, Ar, and Xe. The dominant capture level depends on both of charge state of the ion and ionization energy of the target, and it can be predicted by the classical over-barrier model. The dependence of spectra on the incident charge state and the target gas will be presented and discussed. Identifications of observed lines have not been finished yet, but we have confirmed that the emission lines around 13.5 nm are mainly ascribed to Xe¹⁰⁺ ions.